Healers losing fly had nothing to with edges.

My thoughts were (and still are) that I'm happy with healers having a commonly exploitable weakness in the form of having to rely on dispel-able fly, especially after empowerment became optional. I don't see this changing any time soon.

Fly is crucial in general, not just for exploration, which is why it's so incredibly common in prep form (in very high spell levels, too). It also makes Transmuters even more appealing for exploration too.